18. You have 75.0 mL of 0.10 M HA. After adding 30.0 mL of 0.10 M NaOH, the pH of the HA-NaOH solution is 5.50. What is the Ka value of HA?
(A)1.74 × 10^-8
(B)2.1 × 10^-6
(C)6.0 × 10^-5
(D) 5.6 × 10^-4
(E)6.6 × 10^-7

14. LiI(s) has a heat of formation of -292 kJ/mol and a lattice energy of -753 kJ/mol. The ionization energy of Li(g) is 520 kJ/mol, the bond energy of I2(g) is 151 kJ/mol, and the electron affinity of I(g) is -295 kJ/mol. Use these data to determine the heat of sublimation of Li(s) to be . (A)411 kJ(B)-411 kJ(C)109 kJ (D) -109 kJ (E)161 kJ

15. Which of the following statements is correct? (A)In HF, its bonding molecular orbital has greater H 1s character than fluorine 2p character (B) The bond strength of C2 2- is expected to strengthen as an electron is removed to form the positive charged ion (C) The bond strength of H2 is expected to increase as an electron is removed to form the positive charged ion (D) The order of increasing bond length is CO2+ > CO+ > CO (E)The bond order of CO+ is 3

16. Which of the following statements is correct? (A)HBr has boiling point higher than Kr and Cl2(B)HF has freezing point higher than H2O and NaCl (C) Cl2 has vapor pressure lower than Br2 and I2 (D) CO has freezing point lower than N2 and CO2 (E)HBr has boiling point higher than HF and HCl

17. What is the osmotic pressure of an aqueous solution containing 1.0 g/L of a protein (molar mass = 9.0 × 104 g/mole) and its density of the solution being 1.0 g/cm3 at 25℃? (R = 0.08206 L*atm*mol-1*K-1) (A)0.200 torr(B)0.030 torr(C)0.003 torr (D) 0.400 torr (E)0.0003 torr

19. Kf for the complex ion Ag(NH3)2 + is 1.7 × 107 . Ksp for AgCl is 1.6 × 10-10. Calculate the molar solubility of AgCl (in mol/L) in 1.0 M NH3. (A)1.5 × 10-4(B)1.5 × 10-3- (C)1.5 × 10-2 (D) 4.7 × 10-2 (E)4.7 × 10-3

20. What is the  for H2O(g) + (1/2)O2(g) ←→ H2O2(g) at 600. K using the following data: H2(g) + O2(g) ←→ H2O2(g) K = 2.3 × 106 at 600. K 2H2(g) + O2(g) ←→ 2H2O(g) K = 1.8 × 1037 at 600. K? (A)-7.1 × 104 J/mol(B)1.4 × 105 J/mol(C)1.1 × 105 J/mol (D) 7.9 × 103 J/mol (E)1.0 × 103 J/mol

21. Which of the following statements is correct? (A)For 2H2(g) + O2(g) → 2H2O(l), its  is larger than 0 (> 0)(B)The So of C2H5OH(l) is larger than the So of C2H5OH(g) (C)One mol N2 (at STP) has more positional probability than 1 mol N2 at 100 K, 2.0 atm. (D) The sign of  for the process of H2O(l) → H2O(g) is positive (+). (E)At constant T and P, the change with  is not a spontaneous process.

22. An electrochemical cell consists of a standard hydrogen electrode and a copper metal electrode. What is the potential of the cell at 25℃ if the copper electrode is placed in a solution in which [Cu2+] = 2.5 × 10-4 M. [Note: Cu2+(aq) + 2e- → Cu(s), E0 = 0.34 V] (A)0.23 V(B)-0.16 V(C)0.018 V (D) 0.26 V (E)0.059 V

23. Which of the following compound is not going to dissolve in carbon tetrachloride? (A)CO2(B)CH2=CH2(C)NH4NO3 (D) KrF2 (E)C6H14 (Hexane)

24. Phosphorus-32 (P-32) is a commonly used radioactive nuclide in biochemical research, particularly in studies of nucleic acids. The half-life of P-32 is 14.3 days. What mass of P-32 is left from an original sample of 175 mg of Na3 32PO4 after 35.0 days? Assume the atomic mass of 32-P is 32.0. (A)6.22 mg(B)62.20 mg(C)0.12 mg (D) 1.24 mg (E)12.44 mg